The expression of many inducible genes is regulated at the level of mRNA transcription. The promoter regions of these genes are comprised of regulatory sequences that bind a specific combination of transcription factors. The aim of the present project is to identify and clone novel transcription factors specific for individual members of the TNF/CD4O ligand superfamily. We will use a novel selection system to screen cDNA libraries for proteins which can transactivate expression of antibiotic resistance in the fission yeast, S. pombe, from a target TNF/NGF receptor superfamily promoter. In phase I the concept of this novel transcription factor screen will be reduced to practice. Reporter constructs utilizing the TNF promoter to drive the neomycin phosphotransferase gene will be constructed and transformed into S. pombe to determine baseline sensitivity to the neomycin analog G418. Next the gene for SP1 transcription factor will be cloned into our cDNA library expression vector and its ability to confer G418 resistance on the strain bearing the TNF promoter construct will be demonstrated. in Phase II this system will be used to identify and clone novel TNF/CD4O ligand superfamily transcription factors starting with the CD4O ligand. Inhibition of these transcription factors offers a novel means for immune intervention.